I think the right time to apply through a company portal is when you already have had conversations with folks at the company (hiring managers, recruiters, other team members) and are just "checking the box".
Definitely agree, hope I never have to apply via a portal again.
I would still probably refuse at this point, on grounds of having done this in the past and being "ghosted", even though there was prior conversations.
If a company is interested in me, they won't make me jump through hoops. On the other hand, I'm quite experienced and popular in the job market, so things might be different for other folks.
Definitely agree, hope I never have to apply via a portal again.